The present invention relates to a device for the assembly of microelectromechanical systems (MEMS).
Assembly of MEMS is recognized as difficult for three principal reasons. First, the optical imaging methods commonly used to image small MEMS parts during assembly lack sufficient resolution and depth of field to make accurate imaging of the very small parts practical. Secondly, the parts undergoing assembly are usually manipulated with a micromanipulator equipped with a small set of grippers. The conventional micromanipulator has barely the control necessary for assembly of small mechanical and electromechanical parts. Thirdly, most light microscopes do not have stages of sufficient axes of freedom to manipulate the device so that it is placed properly for precise placement of parts by the grippers located on the micromanipulator.
U.S. Pat. No. 5,559,329 issued Sep. 24, 1996 describes an apparatus for measuring the interfacial properties of fiber-matrix composites. The apparatus includes a linear motion feedthrough for pushing an indentor on a fiber end, a load cell for sensing indentor load and a scanning electron microscope (SEM) for magnifying the material in order to align the indentor with a fiber end undergoing testing. The SEM includes a vacuum chamber for housing the indentor, the load cell and a hot stage module. Data acquisition and recording devices as well as an imaging computer for recording images of the materials during testing are also described.
It is an object of the present invention to relate the capabilities of the devices described in the foregoing U.S. Pat. No. 5,559,329 to the field of MEMS assembly through the presentation of a novel MEMS assembly device that utilizes the general approach of this patent.
According to the present invention there is provided a novel MEMS assembly and testing system that utilizes a scanning electron microscope (SEM) having 5 axes of freedom as the imaging instrument. This imaging instrument has a resolution and depth of focus about 100 times greater than currently used optically based imaging systems. Microgrippers or other tools mounted at the end of a linear motion feed through device having a motion resolution of about 10 nanometers are used as the manipulator. All of the assembly features are located inside of a vacuum chamber to permit operation of the SEM imaging system. A variety of other auxiliary devices that support the MEMS assembly and testing system are also included to enhance the capabilities thereof.